Treatment of sylvinite ores



United States Patent 3,452,867 TREATMENT OF SYLVINITE ORES William T.Bishop, Wilmington, DeL, assignor to Hercules Incorporated, Wilmington,DeL, a corporation are not intended to limit the present inventionbeyond the scope of the appended claims.

Examples 16 of Delaware 5 These runs were carried out in order todetermine the No Drawing. Filed Mar. 30, 1967, Ser. No. 626,943 effectof various slime inhibitors and the recovery of KCl Int. Cl. B01d 21/01from ores containing same. CL 209-166 6 Clalms A sample of minus 10 meshsylvinite ore from the Carlsbad district of New Mexico was scrubbed in asaturated 10 brine solution of the ore and then screened to removeABSTRACT OF THE DISCLOSURE the minus 30 mesh fraction. This removed aportion of The present invention relates to a improvement i the originalclay slimes from the ore. Then the partially th process f eparating Kclf o 1 i i ores i h deslimed ore, at about 50% solids in the saturatedbrine the aid of a mineral collector, the ore containing slimesolution,was thoroughly mixed for two minutes with the forming clay withinterferes with the function of the lime inhibitor along with 0.11 poundCarbowax 550 mineral collector. The improvement comprises carrying(methoxyl polyethylene glycol of approximately 550 out the separation inthe presence of an acrylamide-beta molecular weigh The amounts ofmaterials Used in methacrylyloxyethyltrimethylammonium methyl sulfatethese runs were per ton of the partially deslimed ore on copolymer whichcopolymer serves to minimize the ada dry weight basis. Then 0.5 poundcoal tar creosote (Barverse effect of the clay on the mineral collector.rett No. 634) was added and the mixing continued for 5 minutes. At thispoint amine collector (distilled hydrogenated tallow amine acetate,commercially available as The present invention relates to a process oftreating Armac HTD) was added and the mixing continued for sylviniteores, and more particularly to a flotation proc- 2 minutes. Theresulting ore pulp was then transferred to ess of recovering sylvite(KCl) from sylvinite ores. a flotation cell, and 0.07 poundmethylisobutyl carbinol Sylvinite ores contain various amounts of KCland added prior to floating. The KCl concentrate in the froth NaCl(halite). Typical of such sylvinite ores are those that formed wasremoved from the surface of the pulp in the Carlsbad district of NewMexico. Sylvinite ores liquor. also contain small amounts, usually onthe order of up Further details appear in table hereinafter.

TABLE Percent K01 iu Slime inhibitor Percent Ex. Concen- Tail- K01 No.Name 1 Amount 2 trate ings recovery 1 None None 91.3 23.7 41. 2 2Commercial slime inhibitor.-- 0.11 94.3 3.1 94.3 3... 94% acrylamide, 6%MTMMs. 0.11 94. 4 0. 9 98.2 4 83% acrylamide, 17% 1.10 95.6 0.6 98.3

MTMMS.

Example 2 used as SEPARAN NP an acrylamide-based anionic slime inhibitoravailable commercially 10.

to about 5% or 6%, water-insoluble clay which forms a slime thatinterferes with separating KCl from the ore.

Froth flotation processes are used commercially to recover KCl from theores by flotating the KCl from the NaCl. In this process finely groundore is mixed with a saturated solution of the soluble constituents(usually insoluble constituents such as e.g. clays are also present) ofthe ore and various flotation (collection) and auxiliary agents areadded. The collection agent causes the separation of the KCl from theore. The clay adsorbs a substantial amount of the mineral collector andthus seriously interferes with the separation process. Although it isconventional practice to employ a mechanical desliming step, stillenough clay remains to substantially hinder the separation process.

In accordance with the present invention it has been found that theaddition to sylvinite ores of a small amount of a certainacrylamide-beta methacrylyloxyethyltrimethylammonium methyl sulfate(acrylamide-MTMMS) copolymer substantially increases the KCl recoveryfrom the ores. Apparently the copolymer acts as a blocking agent or ablinding agent to adsorption by the clay of the KCl collector.

The following examples wherein percent and parts are by weight unlessotherwise indicated illustrate various embodiments of the presentinvention. These examples From the foregoing examples it is readilyapparent that the particular copolymer of the present invention, ascompared with prior art polymers, enables the recovery of asubstantially higher percentage of KCl from sylvinite ores and thereforeis a significantly superior slime inhibitor. Very small amounts ofcopolymer of the present invention give substantially increased KClrecovery. Usually the amounts will be about 0.01-0.5, preferably about0.05-0.20 pound per ton dry weight basis by weight of the total amountof ore treated.

Although the terms clay and slime-forming clay have been used herein andin the prior art, the present invention is not limited thereto butincludes any materials which interfere with the performance of themineral collector, which interference the copolymer of the presentinvention lessens. These objectionable slime-forming materials aresometimes referred to in the art as insoluble clay-like minerals.

Although, for the sake of ease of understanding, the present inventionis described herein for the most part with reference to a flotationprocess of concentrating KCl in sylvinite ores, the invention is notlimited thereto. More specifically the present invention is applicableto KCl concentrating processes in general including e.g. those oftenreferred to in the art as flotation, settling, and dissolution processesin general.

The copolymer slime inhibitor of the present invention consists byweight thereof essentially of 99 %20% acrylamide and 1%-80% MTMMS,preferably about 97%- 50% acrylamide and 3%50% MTMMS, about 95% 60%acrylamide and %40% MTMMS being specifically preferred.

Preparation of the particular copolymer employed in the presentinvention is not claimed herein nor is it per se a part of the presentinvention. However, the preparation of said copolymer is quiteimportant. In fact, applicant knows of only one process which willproduce a product having the properties of the particular copolymerapplicable in the present invention. For the sake of completeness thisprocess will now be disclosed. It may be referred to as precipitationpolymerization.

The precipitation process broadly comprises polymerizing butanol,aqueous acetone or aqueous tertiary butanolacetone in the substantialabsence of air while agitating the solution to give a copolymer productthat can be isolated by filtration, the aqueous tertiary butanol andaqueous acetone being solvents for the monomers but nonsolvents for thecopolymer product.

Several of the conditions of this precipitation polymerization processare critical, and these conditions will now be discussed.

The solvent for the monomers must be aqueous tertiary butanol, aqueousacetone or aqueous tertiary butanolacetone (i.e. mixtures of water withtertiary butanol or acetone alone or with both). The concentrations ofwater in said mixtures must be 30%65%, preferably 45%- 60%, by weight ofsaid mixtures.

The polymerization reaction temperature must be 0 C.- 60" C., preferably0 C.40 C.

The polymerization may be carried out either in the presence or absenceof a polymerization catalyst (initiator), but preferably apolymerization initiator will be used. Both the types and amounts offree radical initiator applicable are well known in this art. Peroxygencompounds are quite suitable, including e.g. ammonium persulfate,potassium persulfate and hydrogen peroxide. Other free radical initatorsinclude e.g. u,ot'-axo-bis-isobutyronitrile. The peroxygen initators maybe used alone or in combination with activators (also well known in thisart) including e.g. sodium bisulfite, sodium thiosulfate,tetramethylenediamine, thiourea and ferrous chloride, said combinationforming a redox system. The amount of initator usually will not exceed0.5%, preferably is 0.05%0.2%, 0.05% being specifically preferred, byweight of the combined weight of monomers.

Although not necessary, preferably the precipitation polymerization iscarried out in the presence of a salt dissolved in the polymerizationreaction mixture. By polymerizing in the presence of a salt, or a buffersystem comprising one or more salts in combination with another materialto complete the buffer system, recovery of the copolymer product issubstantially facilitated. These salts and buffer systems include, e.g.,(1) alkali metal and ammonium acetates, carbonates, bicarbonates,chlorides, phosphates, sulfates, bisulfates, borates; (2) buffer sys--terns comprising (2.) mixtures of weak acid or weak base and their saltsincluding (b) phthalates, citrates, borates, phosphates, acetates,ammonium hydroxide, ammonium acetate, ammonium chloride, (c) specificcombinations including mixtures of boric acid-borax, citric acid-sodiumacid phosphate, sodium carbonate-sodium bicarbonate, ammoniumchloride-ammonium hydroxide, ammonium acetate-ammonium hydroxide; or (3)any combination of -(1), and (2).

The amount of salt which may be used is about 0-.1%- 2.0% preferablyabout 0.2%0.7%, by weight of the reaction mixture. If the amount of saltexceeds about 2.0%, usually there is a tendency for the granules of thepolymeric product to agglomerate in the polymerization reaction mixture.The manner of adding the salt and the point at which it is added are notcritical.

The following is a specific example wherein the precipi tation processwas used in preparing the particular copolymer applicable in the presentinvention.

To a glass reactor were charged 116 parts of distilled water, 104 partsof acrylamide, 129 parts of tertiary butanol, 3.9 parts of TergitolNP-14 (nonylphenyl polyethylene glycol ether), 92.4 parts of a 23%aqueous solution of MTMMS, and 0.05 part of potassium persulfate. The pHwas adjusted to 5.3 by addition of NH OH. The solution was heated to 45C. The atmosphere and dissolved air were replaced with nitrogen by aseries of evacuations and repressurizations. The pressure was thenadjusted to 148 mm. to maintain reflux at 45 C. Then 6.26 parts of a 1%aqueous solution of tetramethylethylenediamine was added at a uniformrate during 1.5 hours. Refiuxing the reaction mixture was continued foran additional 1.5 hours. Polymerization occurred and the copolymerprecipitated during this 3-hour period. The copolymer was washed Withacetone and dried in a vacuum oven at 50 C. There was obtained 130 partsof copolymer containing 93.5% solids. It contained 19 weight percentMTMMS and 81 Weight percent acrylamide (dry basis).

Although the copolymer slime inhibitor in accordance with the presentinvention may be added in dry form to the ore being treated, it ispreferred to add it as an aqueous solution in order to get faster andmore complete dispersion thereof throughout the ore.

What I claim and desire to protect by Letters Patent is:

1. In a process of separating KCl from sylvinite ores containing KCl andobjectionable slime-forming clay by a KCl concentration process whereinsaid separation is carried out with the aid of a mineral collector addedto the ore, the improvement which comprises adding to the ore beforeaddition thereto of the mineral collector a water solubleacrylamide-beta methacrylyloxyethyltrimethylammonium methyl sulfatecopolymer as a slime inhibitor.

2. In a process of separating KCl from sylvinite ores containing KCl andobjectionable slime-forming clay by a froth flotation process wherein amineral collector and other auxiliary agents are added to the oreslurried in water substantially saturated with the soluble constiucutsof the ore and the resulting slurry subjected to a froth flotationprocess, the improvement which comprises adding to the ore beforeaddition thereto of the mineral collector a water solubleacrylamide-beta methacrylyloxyethyltrimethylammonium methyl sulfatecopolymer as a slime inhibitor.

3. Process of claim 2 wherein the amount of said acrylamide-betamethacrylyloxyethyltrimethylammonium methyl sulfate copolymer employedis about 0.01-0.30 pound per ton of ore treated on a dry weight basis.

4. Process of claim 2 wherein the copolymer consists by weight thereofessentially of 99%20% acrylamide and 1%80% betamethacrylyloxyethyltrimethylammonium methyl sulfate.

5. Process of claim 2 wherein the copolymer consists by weight thereofessentially of 97%-50% acrylamide and 30%50% betamethacrylyloxyethyltrimethylammonium methyl sulfate.

6. Process of claim 2 wherein the copolymer consists by weight thereofessentially of %-60% acrylamide and 5%40% betamethacrylyloxyethyltrimethylammonium methyl sulfate.

References Cited UNITED STATES PATENTS 2,740,522 4/ 1956 Aimone 209-1062,923,408 2/ 1960 Williams '209-166 3,023,162 2/ 1962 Fordyce 21052 X3,321,649 5/1967 De Benedictis 209166 X HARRY B. THORNTON, PrimaryExaminer. ROBERT HALPER, Assistant Examiner.

'gz g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,452,867 Dated July 1, 1969 Inventofls) William T. Bishop (Case 11) Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 15, "with" should read --which- Column 1, line 50,"flotating" should read -floating Column 2, Table opposite example 4under column Amt. (b)

"1. l0 should read -O. 10-- Column 3 following line 16 after"polymerizing" insert -a solution of acrylamide and MTMMS monomers inaqueous tertiary-- Column 3 line 41, "axo" should read -azo Column 4,line 42 Claim 2 "constiuents" should read -constituents Column 4, line58, Claim 5, "30%50%" should read 3%50%-- SIGNED AN.) SEALED MAR 2 41970(SEAR Amen:

EdmdMFlemherJr.

WILLIAM 1!. BGHUYHJR, JR. Lmmlgoffiw Gomissioner or Patents

